How to temporarily fix a leaking pipe under the sink

Shut off the water, clear out the cabinet, and dry the pipes enough to see the first wet point before you touch anything. Then match the leak to the pipe type: a loose slip-joint or fitting may only need a slight snug-up, while a cracked pipe, pinhole, or badly corroded chrome trap usually needs a temporary wrap or the water left off until replacement. If the leak is on a supply line or the part is split or moving, stop patching and keep the water off.

Start by shutting off water and spotting the first wet point

1. Shut off the right water first. If the leak is on a supply line, close the sink’s shutoff valve; if you can’t isolate the leak cleanly, turn off the main water supply. Then open the faucet briefly to relieve pressure if you shut off a supply line.

2. Clear the cabinet and dry it out before you touch the leak. Pull out everything under the sink, place a bucket or towels underneath, and wipe away standing water so you can see where the first wet point appears. That first wet point matters because water often runs along a pipe before it drips onto the cabinet floor.

3. Check when the leak appears. If it only shows up when water runs down the drain, look first at the P-trap, tailpiece, slip-joint nut, or another drain connection. If it starts as soon as the faucet runs under pressure, the problem is more likely on the supply side or in a flexible supply line.

Is this a loose joint, a bad washer, or a cracked pipe?

4. If you can separate the joint easily and the washer is the problem, replace or reseat the washer if you already have the correct part on hand. Replacement washers are commonly the part that stops seepage at a drain connection. If the joint comes apart cleanly and the pieces are still in good shape, that is a cleaner temporary fix than wrapping over the problem.

5. If the fitting resists, stop. Overtightening can crack plastic parts, distort the washer, or make the leak worse. A fitting that keeps turning without sealing, or one that feels stressed when you tighten it, is telling you the part may already be damaged.

The temporary fix that fits the leak type

1. Tighten only the loose connection, and only a little. If a slip-joint nut or similar fitting is leaking from a minor seep, give it a small snug-up by hand or with light tool pressure. Stop as soon as it resists. If the leak does not change after that, do not keep cranking on it.

2. Use a patch that matches the damage, not the material you happen to have on hand. For a small crack in PVC or ABS, a rubber repair clamp or a wrap can slow the leak if the pipe is stable and the crack is small. For a pinhole in copper, self-fusing silicone tape or epoxy putty can sometimes slow the seep if the pipe is dry enough and the hole is tiny. For a corroded chrome trap, the safer temporary move is usually to leave the water off and replace the part, because corrosion keeps spreading and the metal may fail again.

3. Treat supply lines differently. If a flexible supply line is leaking, the safest temporary fix is usually isolation rather than patching. Shut the valve, relieve pressure by opening the faucet, and keep that line out of service until it can be replaced with the correct part.

4. Use epoxy putty or repair tape only on a surface you have dried as well as you can. LOCTITE’s repair guidance for a sink pipe leak starts with placing a bucket under the sink, turning off the water supply line, and cleaning the pipe surface before applying epoxy putty or repair tape. That lines up with the general rule here: patches need a clean, dry surface and a leak that is stable enough to wrap.

What to dry, what to wrap, and what not to use

1. Dry the area enough for the wrap, tape, or epoxy to hold. Wipe off standing water first, then dry the pipe around the leak and a little beyond it. If you can, let it air-dry for a few minutes before you apply anything. Grease, soap film, and constant dripping weaken the bond.

2. Match the product to the surface. Self-fusing silicone tape works best when the pipe is dry or nearly dry and the wrap can stretch onto itself. Epoxy putty also needs a clean surface to bond well. A rubber repair clamp works better than tape on a small crack because it seals by compression, but it still needs the pipe to be stable and not actively spraying.

3. Skip fixes that fail quickly on wet, moving, or badly damaged parts. Regular tape is usually a poor short-term fix for an under-sink leak because it does not seal well on wet plumbing and often peels off. Split plastic, badly rusted chrome, and cracked fittings that flex when the drain moves are all poor candidates for a wrap.

4. Use the product directions on the package you have in front of you. Product formulas and cure times can change, so check the current label or official instructions before relying on any specific repair product.

How to test the repair without turning a drip into a flood

1. Test the repair with short water runs, not a full sink. Start with a brief run of water and watch the repair point closely. Then stop the flow and look again for fresh wetness on the joint, the wrap, and the cabinet floor.

2. Repeat the check once or twice if the first test looks dry. Run the water again for a short drain cycle and watch the same spots. Also feel along the bottom edge of the cabinet, because some leaks travel there before they show up as a puddle.

3. Decide whether the repair is holding. If the patch stays dry and no new drip appears lower down, the temporary fix is doing its job for now. If the leak returns right away, gets wetter under use, or starts leaking from a different seam, stop and leave the water off until the part is replaced.

4. If you see a supply line leak, a split pipe, or a corroded trap still weeping after the test, do not keep rewrapping it. That usually means the damage is beyond a temporary patch.

When to stop and leave the water off

1. Leave the water off if the leak is on a supply line that starts leaking as soon as pressure returns. A supply-side leak is more likely to fail again under pressure than a drain-side seep.

2. Leave the water off if the pipe wall is split, the fitting is cracked, or the chrome trap is heavily corroded. Those problems usually come back even if a patch slows them for a while.

3. Leave the water off if the fitting resists tightening or the leak gets worse as you turn it. That usually means the washer is damaged, the threads are failing, or the plastic is already stressed. Forcing it can turn a small seep into a broken joint.

4. If the leak is only a slow seep from a sound pipe and you can dry the area well, a temporary fix may buy you time until you can replace the part. If the damage is structural, the temporary fix is just a delay, not a solution.